SCIENCE

Life Without Left Turns

January 11, 2011

I once was hit while making a left turn. The driver of a car coming in the opposite direction ran the red light, striking the rear of the minivan I was driving, and spinning it 180 degrees. I walked away, badly shaken. My mom's minivan was totaled.

I still hate making left turns.

I'm not the only one. UPS minimizes left turns for its delivery trucks to save on fuel. (And it works, as the Mythbusters demonstrated last year.) In the 1960s, the state of Michigan designed an intersection known as the "Michigan left" that prevents people driving on side streets from making left turns onto a multi-laned divided road; if they wish to go left, they'll first have to go right and then make a U-turn. And superstreets, or restricted crossing U-turns, which are found in some other parts of the country, such as North Carolina, work in a similar way, preventing left turns. It's never really caught on, though, since it seems to be a big inconvenience.

However, a new study from North Carolina State University says that superstreets are actually more efficient than traditional intersections. The researchers collected data from three superstreets in North Carolina that had traffic lights and looked at travel time for both right and left turns as well as passing straight through. They also examined collision data from 13 superstreet intersections in that state that didn't have traffic lights.

“The study shows a 20 percent overall reduction in travel time compared to similar intersections that use conventional traffic designs,” says NCSU engineering professor Joe Hummer, one of the researchers who conducted the study. “We also found that superstreet intersections experience an average of 46 percent fewer reported automobile collisions—and 63 percent fewer collisions that result in personal injury.”

A life without left turns is starting sound better and better.